sci.physics.particle

On Mar 16, 6:04=A0pm, Tom Roberts wrote:

>
> I mentioned the solar atmosphere because some people think the Shapiro
> time delay is due to it (such an atmosphere has an altitude-varying
> index of refraction, which _could_ behave like the Shapiro time delay).
> It's just that actual measurements of the solar atmosphere and its
> properties completely refute that claim.

Another way to look at it is that GR *predicts* the
solar plasma because energy density has a relation
to a volume of space-time.

Bruno Bertotti seemed to have learned more about solar
plasma than light bending from the Cassini path, IMHO.

<>
http://www.universetoday.com/2003/10/03/cassini-confirms-general-relativity/=


<< The plasma noise is highly variable over all time
scales, depending primarily on solar activity, in par-
ticular solar flares, coronal holes, and solar rotation.
Because of stochastic plasma variability, the real as-
sessment of how well the dual-band plasma correction
works can be determined only by doing it. >>
"Measurement of the PPN Parameter with Radio Signals
from the Cassini Spacecraft at X- and Ka-Bands"
http://www.slac.stanford.edu/econf/C041213/papers/0305.PDF


<< It is interesting to note that, since plasma
effects near the Sun need to be eliminated to
better than one part in 10^4, the usual expression
for the frequency correction (7) (where L is
the optical path with suitable refractive index)
is not accurate enough. Relativistic corrections
O.v=3Dc/ are needed, in particular the one arising
from the difference between the emission and
the receiving time. The fully relativistic
expression of the Doppler effect in a moving medium
has been derived with the Hamiltonian formalism in [31]. >>
"Doppler Measurement of the Solar Gravitational Deflection"
http://www.sp.ph.ic.ac.uk/~giacomo/Papers/doppler_abs.html

It may be a half full glass to some, a half empty glass
to others but I see little in that to "completely refute"
the effects of the solar plasma.

Sue...

>
> Tom Roberts